/// @tags: DPonContiguousBlocks
#include <cstdio>
#include <iostream>

using namespace std;

namespace BlueQuantum {

typedef long long LL;

int const N = 2e3 + 5, mod = 1e9 + 7;

LL f[N][N];

inline int main() {
  int n, s, t;
  cin >> n >> s >> t;
  f[1][1] = 1;
  for (int i = 2; i <= n; ++i) {
    for (int j = 1; j <= i; ++j) {
      if (i != s && i != t) {
        f[i][j] =
            (f[i - 1][j + 1] * j % mod + f[i - 1][j - 1] * (j - (i > s) - (i > t))) % mod;
      } else {
        f[i][j] = (f[i - 1][j] + f[i - 1][j - 1]) % mod;
      }
    }
  }
  cout << f[n][1];
  return 0;
}

}  // namespace BlueQuantum

int main() {
#ifndef ONLINE_JUDGE
#ifdef LOCAL
  freopen("/tmp/CodeTmp/testdata.in", "r", stdin);
  freopen("/tmp/CodeTmp/testdata.out", "w", stdout);
#else
  freopen("P5999 [CEOI2016] kangaroo.in", "r", stdin);
  freopen("P5999 [CEOI2016] kangaroo.out", "w", stdout);
#endif
#endif

  ios::sync_with_stdio(false), cin.tie(NULL), cout.tie(NULL);
  return BlueQuantum::main();
}
